In Reply: Dr Oudiz suggests that there is a
strong correlation between the amount of calcium deposition in a coronary
artery detected by EBCT and the degree of coronary artery stenosis detected
by coronary artery angiography. Oudiz cites the study of Agatston et al1 to support this claim, but the r values obtained in that study ranged only from 0.62 to 0.68. Moreover,
there was tremendous variability about the regression lines, further demonstrating
that the correlation is weak. These findings are not surprising given the
difficulty in accurately quantifying the volume and geometry of calcium in
coronary artery plaques by EBCT,2,3
and the fact that calcium represents only a portion of the composition of
a plaque.3